Soil nutrient status and fertility evaluation of typical taro producing areas in Shaoguan City

Objective To better understand the soil fertility status in typical taro producing areas in Shaoguan City, Guangdong Province, and provide suggestions for soil nutrient management in taro producing areas.

Method The 0−30 cm soil samples were collected from taro rhizosphere in Laojun Village of Guitou Town, Guanpotan Village and Nongzhuang Village of Langtian Town from Shaoguan City, to determine the physical and chemical properties. Principal component analysis and correlation analysis were conducted to select the key indicators that best represent local soil fertility entering into minimum data set. All indicators were normalized using membership functions, and soil quality indices were calculated for soil fertility evaluation.

Result The soils in three taro producing areas were all acidic with suitable bulk density (1.17 g·cm⁻³) and texture, but with low cation exchange capacity (CEC, 9.17 cmol·kg⁻¹). The contents of available P (54.20 mg·kg⁻¹), Cu (2.07 mg·kg⁻¹), Fe (186.33 mg·kg⁻¹), Zn (1.87 mg·kg⁻¹) were rich, while the contents of available Mn (4.21 mg·kg⁻¹), B (0.12 mg·kg⁻¹), Mo (0.10 mg·kg⁻¹) were deficient or extremely deficient. The contents of other nutrients were at moderate to above-average levels. Among the three taro producing areas, there were significant differences in the percentage of soil grain size, contents of alkali-hydrolyzed N, exchangeable Ca, and exchangeable Mg, whereas the differences in other indicators were not significant. Seven indicators were selected to build the minimum data set for soil fertility evaluation, including alkali-hydrolyzed N, sand, clay, exchangeable Ca, available B, and available Fe contents as well as CEC. The evaluation results indicated that the soil fertilities of the three taro producing areas were at moderate levels, and the contents of alkali-hydrolyzed N and exchangeable Ca were the main limiting factors.

Conclusion The overall soil fertility level of typical taro producing area in Shaoguan City is moderate, with poor soil nutrient retention capacity and deficiencies in trace elements, such as available Mn, B and Mo. Therefore, it is important to use organic fertilizers and micronutrient fertilizers during taro cultivation. Balanced fertilization shall be practiced to improve soil properties and enhance its nutrient retention capacity.